A-d converter and a-d convert method

Abstract

There is provided an A / D converter that outputs a digital output signal obtained by digitalizing an analog input signal. The A / D converter includes a bit selecting section that selects a conversion object bit from a high-order bit to a low-order bit of the digital output signal in order, a threshold-value controlling section that determines a threshold data expressing a boundary value between zero and one of the conversion object bit, a D / A converting section that digital-to-analog converts the threshold data and generates an analog threshold value, a comparing section that compares, at a plurality of different timings in a conversion time interval determining a value of the conversion object bit, the analog input signal and the analog threshold value and outputs a plurality of comparison results at the timings, and a bit determining section that determines the value of the conversion object bit.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This is a continuation in-part application of Ser. No. 11 / 520,436 filed on Sep. 13, 2006, the contents of which are incorporated herein by reference.BACKGROUND[0002]1. Field of the Invention[0003]The present invention relates to an A-D converter and an A-D convert method. More particularly, the present invention relates to an A-D converter and an A-D convert method for outputting a digital output signal obtained by digitalizing an analog input signal.[0004]2. Related Art[0005]An A-D converter converts an analog signal into a digital signal. The A-D converter is classified into a single bit mode in which an input signal is quantized by one bit in one clock and a multiple bit mode in which an input signal is quantized by multiple bits in one clock. The A-D converter with a single bit mode includes, for example, a successive-approximation type A-D converter and a delta-sigma type A-D converter. The successive-approximation type A-D converter ...

AI Technical Summary

Benefits of technology

[0009]That is, according to the first aspect of the present invention, there is provided an A/D converter that outputs a digital output signal obtained by digitalizing an analog input signal. The A/D converter includes: a bit selecting section that selects a conversion object bit from a high-order bit to a low-order bit of the digital output signal in order; a threshold-value controlling section that determines a threshold data expressing a boundary value between zero and one of the conversion object bit on the basis of an already-determined value of a higher-order bit than the conversion object bit; a D/A converting section that digital-to-analog converts the threshold data and generates an analog threshold value; a comparing section that compares, at a plurality of different timings in a conversion time interval determining a value of the conversion object bit, the analog input signal and the analog threshold value and outputs a plurality of comparison results at the timings; and a bit determining section that determines the value of the conversion object bit on the basis of the plurality of comparison results.

[0010]According to the second aspect of the present invention, there is provided an A/D converter that outputs a digital output signal obtained by digitalizing an analog input signal. The A/D converter includes: a plurality of comparators of which each compares the analog input signal and an analog threshold value according to a specified digital threshold data; a high-order field determining section that narrows down a data value corresponding to a high-order field for a predetermined bit number in the digital output signal on the basis of a plurality of comparison results obtained by supplying different threshold data to the plurality of comparators; a low-order field computing section that computes a plurality of candidate values for a data value corresponding to a low-order field for a predetermined number of bits located at a side lower than the high-order field by means of the plurality of comparators; a low-order field determining section that determines the data value corresponding to the low-order field on the basis of the plurality of candidate values; and a timing controlling section that causes, when computing the plurality of candidate values of the data value corresponding to the low-order field, a first comparator among the plurality of comparators to compare the analog input signal and the analog threshold value at a first timing in a conversion time interval determining a value for one bit and causes a second comparator among the plurality of co

Problems solved by technology

Meanwhile, the A / D converter may output an incorrect result in some cases when large noises are instantaneously included in the input signal.

However, the A / D converter including such the low-pass filter has a delayed settling time, and thus has a long conversion time.

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